/* GStreamer

 *

 * Copyright (C) 2007 Sebastian Dröge <slomo@circular-chaos.org>

 *

 * gstcontrolsource.c: Interface declaration for control sources

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 */

/**

 * SECTION:gstcontrolsource

 * @title: GstControlSource

 * @short_description: base class for control source sources

 *

 * The #GstControlSource is a base class for control value sources that could

 * be used to get timestamp-value pairs. A control source essentially is a

 * function over time.

 *

 * A #GstControlSource is used by first getting an instance of a specific

 * control-source, creating a binding for the control-source to the target property

 * of the element and then adding the binding to the element. The binding will

 * convert the data types and value range to fit to the bound property.

 *

 * For implementing a new #GstControlSource one has to implement

 * #GstControlSourceGetValue and #GstControlSourceGetValueArray functions.

 * These are then used by gst_control_source_get_value() and

 * gst_control_source_get_value_array() to get values for specific timestamps.

 */

#include "gst_private.h"

#include <glib-object.h>

#include <gst/gst.h>

#include "gstcontrolsource.h"

#define GST_CAT_DEFAULT control_source_debug

GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);

#define _do_init \

  GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT, "gstcontrolsource", 0, \

      "dynamic parameter control sources");

G_DEFINE_ABSTRACT_TYPE_WITH_CODE (GstControlSource, gst_control_source,

    GST_TYPE_OBJECT, _do_init);

static void

gst_control_source_class_init (GstControlSourceClass * klass)

{

}

static void

gst_control_source_init (GstControlSource * self)

{

  self->get_value = NULL;

  self->get_value_array = NULL;

}

/**

 * gst_control_source_get_value: (method)

 * @self: the #GstControlSource object

 * @timestamp: the time for which the value should be returned

 * @value: (out): the value

 *

 * Gets the value for this #GstControlSource at a given timestamp.

 *

 * Returns: %FALSE if the value couldn't be returned, %TRUE otherwise.

 */

gboolean

gst_control_source_get_value (GstControlSource * self, GstClockTime timestamp,

    gdouble * value)

{

  g_return_val_if_fail (GST_IS_CONTROL_SOURCE (self), FALSE);

  if (G_LIKELY (self->get_value)) {

    return self->get_value (self, timestamp, value);

  } else {

    GST_ERROR ("Not bound to a specific property yet!");

    return FALSE;

  }

}

/**

 * gst_control_source_get_value_array: (method)

 * @self: the #GstControlSource object

 * @timestamp: the first timestamp

 * @interval: the time steps

 * @n_values: the number of values to fetch

 * @values: (array length=n_values): array to put control-values in

 *

 * Gets an array of values for for this #GstControlSource. Values that are

 * undefined contain NANs.

 *

 * Returns: %TRUE if the given array could be filled, %FALSE otherwise

 */

gboolean

gst_control_source_get_value_array (GstControlSource * self,

    GstClockTime timestamp, GstClockTime interval, guint n_values,

    gdouble * values)

{

  g_return_val_if_fail (GST_IS_CONTROL_SOURCE (self), FALSE);

  if (G_LIKELY (self->get_value_array)) {

    return self->get_value_array (self, timestamp, interval, n_values, values);

  } else {

    GST_ERROR ("Not bound to a specific property yet!");

    return FALSE;

  }

}